Harry Potter turns 20 on Monday when muggle readers in gowns and glasses from Indonesia to Uruguay will celebrate the birth of a global publishing phenomenon in 1997.

Harry Potter and the Philosopher’s Stone (later renamed Sorcerer’s Stone for the US market) introduced the boy wizard and a magical cast of supporting characters.

Penniless single mother JK Rowling finally succeeded after a series of rebuffs from publishers, and the book became the first instalment of a seven-novel series that has sold 450 million copies worldwide and spawned eight blockbuster films.

The Potter universe now encompasses theme parks in the United States and Japan and a permanent exhibition at London’s Warner Bros Studios, helping to turn Rowling into a multi-millionaire.

No other children’s book has achieved quite as much in terms of both commercial and cultural impact, turning an entire generation of boys as well as girls into enthusiastic readers who would happily join midnight queues at bookshops as each novel came out.

Rowling once told a beaming crowd of Harvard University graduates how she had initially failed “on an epic scale”.

“An exceptionally short-lived marriage had imploded, and I was jobless, a lone parent, and as poor as it is possible to be in modern Britain, without being homeless,” she said..

If some of the early reviews took issue with Rowling’s pedestrian writing and bald characterisation, everyone agreed about the narrative verve on show in the Philosopher’s Stone, starting with the delivery of a letter that will, like alchemy, transform the 11-year-old hero’s life forever.

JK Rowling attends the world premiere of Fantastic Beasts and Where To Find Them in New York.
(AP)

The wealth amassed along the way gives Rowling an estimated fortune of £650 million ($825 million, 743 million euros), according to The Sunday Times newspaper’s 2017 Rich List.

Such riches would have seemed impossible to Rowling in the early 1990s, when she worked as an English teacher in Portugal’s second city Porto.

She spent her free time writing early drafts of the Potter world, but in 1993 split from her husband and left Portugal with her four-month-old daughter.

Rowling continued crafting Harry Potter in Edinburgh sitting on a modest oak chair, part of a mismatched set of furniture which she was given for free while living in subsidised housing.

Such is the magic of the author’s own story, the chair sold in a New York auction last year for $394,000.

“Once you start reading it, you enter a magical world, a world where you could be special, a world with clever things, with the idea that it all just might exist,” Durham University education professor Martin Richardson told AFP.

“The characters become part of the family. It starts to enter the nation’s DNA,” he said.

“I think people will be reading Potter in 20, 30, 40, 60 years time, even if it’s only for the story.”

The seven volumes have been translated into 79 languages in 200 countries, and Monday’s 20th anniversary will feature fancy-dress reading parties around the world starting in Australia and ending in Canada and the US West Coast, at libraries, bookshops and British embassies.

A store assistant holds copies of the book of the play of Harry Potter and the Cursed Child parts One and Two at a bookstore in London.

Marie Lallouet, editor-in-chief of a children’s literature digest at the National Library of France, underlined the scale of the books’ appeal beyond Britain, which already had a rich stock of literature conjuring tales out of the worlds of boarding schools and magic.

“Harry Potter re-validated children’s literature in the eyes of adults, and encouraged an entire generation (of French children) to learn English so that they could read the books as soon as they came out in English,” she said.

Rowling managed to magic “something very powerful” into existence, Lallouet said, by portraying one boy’s struggle to come to terms with his tragic beginnings against the backdrop of an existential struggle of good against evil.

The first print run of the Philosopher’s Stone produced 1,000 copies -- all now highly sought after by collectors -- and earned Rowling a £1,500 contract from Bloomsbury after numerous rebuffs from other publishers.

“I just loved it at first sight. I’d worked with Roald Dahl in his glory days, so I suppose the opening chapters reminded me a little of him,” Barry Cunningham, Rowling’s original publisher at Bloomsbury, told The Daily Telegraph.

A member of staff at Waterstones holds a story written by JK Rowling donated by the author, for the What's Your Story? auction in aid of English PEN and Dyslexia Action, in London.
(AP)

Bloomsbury affected one small change by persuading Joanne Rowling to publish under the nom de plume JK, convinced that boys would shy away from a book written by a woman.

Still, Cunningham was not sure the Philosopher’s Stone would make any money, and urged Rowling to stick to a day job while writing on the side.

“I couldn’t be prouder of the Harry Potter legacy: not only has it made reading cool again, it has shown that families can all enjoy great stories together,” he said.

“We can believe that there is a real purpose to standing up to evil. And, of course, we can find our own magic.”

Famed for creating her much-loved wizarding realm, Rowling has in the real world become a vocal champion of social causes and speaks up frequently for minorities.

“We do not need magic to change the world, we carry all the power we need inside ourselves already: we have the power to imagine better,” the author said in 2008.